1. Field of Invention
The invention relates to a motor-driven vehicle drive control apparatus and method thereof.
2. Description of Related Art
Conventionally, there exists a vehicle driving apparatus that is mounted on an electric car. The vehicle driving apparatus generates a motortorque and transmits the motor torque to a drive wheel. In this vehicle driving apparatus, a motor is driven by a direct current application from a battery at a time of power running (driving), generates the motor torque, is exposed to a torque caused by an inertia of the electric car at a time of regeneration (power generation), generates a direct current, and supplies the electric current to the battery.
Further, there exists a vehicle driving apparatus that is mounted on a hybrid vehicle that serves as a motor-driven vehicle. The vehicle driving apparatus transmits part of an engine torque to a power generator (a power generator motor) corresponding to a first motor-driven machine and the rest of the engine torque to a drive wheel. In this vehicle driving apparatus, the vehicle driving apparatus has a planetary gear unit provided with a sun gear, a ring gear and a carrier. The carrier is connected to the engine, the ring gear is connected to the drive wheel, the sun gear is connected to the power generator, and a rotation output from the ring gear and a motor corresponding to a second motor-driven machine is transmitted to the drive wheel, whereby a driving force is generated.
In the above vehicle driving apparatus, a motor control apparatus is arranged in each vehicle driving apparatus. Both of the motor control apparatuses are structured such that a feedback control in accordance with a vector control computation is executed on a d-q axes model in which an axis d and an axis q are respectively placed in a direction of a magnetic pole pair of a rotor in the motor and in a direction perpendicular to the axis d, at a time of supplying the electric current from the battery to the motor and at a time when the motor-driven vehicle is driven by the motor. Further, when the motor is driven at a high speed in the feedback control, an induced voltage becomes high, and a sufficient motor torque can not be generated. Accordingly, when the motor is driven at a high speed, a weak field control is executed by reducing an amount of magnetic flux formed by the d-axis current.